Experiments relevant to astrophysical jets

Bellan, Paul M.

doi:10.1017/s002237781800079x

Cited by 41 publications

(25 citation statements)

References 56 publications

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“…Magnetic forces associated with this current squeeze together poloidal flux surfaces radially and distend these surfaces axially so plasma frozen to these flux surfaces collimates and becomes a ∼40 km s −1 jet that propagates in the z direction from the electrodes into the chamber. The jet lasts about 20 μs and its flow and collimation agree with predictions based on detailed analytical and numerical consideration of MHD forces (Kumar & Bellan 2009;Yun & Bellan 2010;Zhai et al 2014;Bellan 2018aBellan , 2018b. The jet formation, collimation, and axial lengthening have been observed using a fast movie camera.…”

Section: Introductionsupporting

confidence: 65%

3D Numerical Simulation of Kink-driven Rayleigh–Taylor Instability Leading to Fast Magnetic Reconnection

Wongwaitayakornkul

Bellan

2020

ApJL

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Fast magnetic reconnection involving non-MHD microscale physics is believed to underlie both solar eruptions and laboratory plasma current disruptions. While there is extensive research on both the MHD macroscale physics and the non-MHD microscale physics, the process by which large-scale MHD couples to the microscale physics is not well understood. An MHD instability cascade from a kink to a secondary Rayleigh-Taylor instability in the Caltech astrophysical jet laboratory experiment provides new insights into this coupling and motivates a 3D numerical simulation of this transition from large to small scale. A critical finding from the simulation is that the axial magnetic field inside the current-carrying dense plasma must exceed the field outside. In addition, the simulation verifies a theoretical prediction and experimental observation that, depending on the strength of the effective gravity produced by the primary kink instability, the secondary instability can be Rayleigh-Taylor or mini-kink. Finally, it is shown that the kink-driven Rayleigh-Taylor instability generates a localized electric field sufficiently strong to accelerate electrons to very high energy.

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Section: Introductionsupporting

confidence: 65%

3D Numerical Simulation of Kink-driven Rayleigh–Taylor Instability Leading to Fast Magnetic Reconnection

Wongwaitayakornkul

Bellan

2020

ApJL

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“…This once again indicates the potential of the scalings and similarities in relation to astrophysics. A detailed comparison of the spheromak-produced laboratory jets with astrophysical models can be found in Bellan (2018aBellan ( , 2018b. See also You et al, 2018. The basic configuration of the Caltech experiment is shown in Fig.…”

Section: E Magnetic Arches and Their Stabilitymentioning

confidence: 99%

Exploring astrophysics-relevant magnetohydrodynamics with pulsed-power laboratory facilities

2019

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Laboratory facilities employing high pulsed currents and voltages, and called generally "pulsed-power facilities", allow experimenters to produce a variety of hydrodynamical structures replicating, often in a scalable fashion, a broad range of dynamical astrophysical phenomena. Among these are: astrophysical jets and outflows, astrophysical blast waves, magnetized radiatively dominated flows and, more recently, aspects of simulated accretion disks. The magnetic field thought to play significant role in most of the aforementioned objects is naturally present and controllable in pulsed-power environments. The size of the objects produced in pulsed-power experiments ranges from a centimeter to tens of centimeters, thereby allowing the use of a variety of diagnostic techniques. In a number of situations astrophysical morphologies can be replicated down to the finest structures. The configurations and their parameters are highly reproducible; one can vary them to isolate the most important phenomena and thereby help in developing astrophysical models. This approach has emerged as a useful tool in the quest to better understand magnetohydrodynamical effects in astronomical environments. The present review summarizes the progress made during the last decade and is designed to help readers identify and, perhaps, implement new experiments in this growing research area. Techniques used for generation and characterization of the flows are described. 1 Retired 2 CONTENTS I. Introduction II. Jets and outflows-weak magnetic field A. Generating plasma streams and plasma jets with wire arrays. B. Hypersonic, radiatively cooled hydrodynamic jets and their interaction with the ambient medium C. Hydrodynamic interaction of the jets with a side wind D. Highly-collimated jets produced by ablation of the central area of a metal foil III. Jets and outflows-significant magnetic field A. Magnetically-dominated tower jets B. Formation of energetic ions in a magnetic cavity C. Possible role of axial magnetic field B. Episodic events and internal shocks E. Magnetic arches and their stability F. MHD equilibria stabilized by the shear flow IV. Rotating plasmas-on the way to imitating the accretion discs V. Shock waves A. General comments B. Blast waves and radiative precursors C. Shocks in the colliding streams D. Introducing magnetic field E. Interaction of magnetized streams with clumps and globules VI. Non-MHD effects A. Hall and other two-fluid effects B. Generation of energetic particles C.

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“…The model presented here does not attempt to describe the axial forces that lead to the jet axial motion nor does it attempt to describe the power source driving the jet. Descriptions for how magnetic and hydrodynamic forces cause jet axial motion are given in Bellan (2018aBellan ( , 2018b. How angular momentum is absorbed by magnetic braking in the disk, then convected by the jet, and finally shed elsewhere is discussed in Bellan (2016Bellan ( , 2017; these papers also discuss how accretion converts gravitational potential energy into the electrical power supply that drives the electric current in the jet.…”

Section: Comparison To Previous Modelsmentioning

confidence: 99%

Analytic Model for the Time-dependent Electromagnetic Field of an Astrophysical Jet

Bellan

2020

ApJ

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An analytic model of the time-dependent electric and magnetic fields of an astrophysical jet is presented. These fields satisfy the time-dependent Faraday's law and describe a jet with increasing length. The electric field contains both electrostatic and inductive parts. The electrostatic part corresponds to the rate of injection of toroidal magnetic flux, while the sum of the electrostatic and inductive parts results in the electric field parallel to the magnetic field being zero everywhere. The pinch force associated with the electric current provides a peaked pressure on the jet axis and a pressure minimum at the radius where the poloidal magnetic field reverses direction.

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Experiments relevant to astrophysical jets

Cited by 41 publications

References 56 publications

3D Numerical Simulation of Kink-driven Rayleigh–Taylor Instability Leading to Fast Magnetic Reconnection

3D Numerical Simulation of Kink-driven Rayleigh–Taylor Instability Leading to Fast Magnetic Reconnection

Exploring astrophysics-relevant magnetohydrodynamics with pulsed-power laboratory facilities

Analytic Model for the Time-dependent Electromagnetic Field of an Astrophysical Jet

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